A comparison of finishing systems and duration for spring-born Aberdeen Angus × Holstein-Friesian and Belgian Blue × Holstein-Friesian steers

In Ireland, the majority of dairy cows calve in spring and the male progeny are reared for beef as steers. Over half of all dairy calves are beef crosses with Aberdeen Angus and Belgian Blue representing two extremes in maturity type. The objective of this study was to compare different finishing systems in the autumn/winter of their second year for spring-born steers of contrasting maturity type. A total of 80 spring-born calves, 40 Aberdeen Angus × Holstein-Friesian (AA) and 40 Belgian Blue × Holstein-Friesian (BB) were reared together to 16 months of age. They were then blocked on live weight within breed type and assigned to a pre-experimental slaughter group and to four finishing groups namely: (i) pasture only for 94 days to slaughter, (ii) concentrates ad libitum indoors for 94 days to slaughter, (iii) pasture only for 94 days followed by concentrates ad libitum indoors for 95 days to slaughter, and (iv) concentrates ad libitum indoors for 189 days to slaughter. After slaughter, the 6–10th ribs joint was separated into its component tissues and a sample of m. longissimus was chemically analysed. Mean slaughter weights and carcass weights per day from arrival were 922 and 957 (s.e. 10.6)g, and 476 and 511 (s.e. 6.1) g for AA and BB, respectively. Corresponding carcass weights, kill out proportions, ribs joint fat and muscle proportions, and m. longissimus lipid concentrations were 300 and 322 (s.e. 3.9) kg, 515 and 534 (s.e. 2.4) g/kg, 181 and 121 (s.e. 4.2) g/kg, 605 and 666 (s.e. 4.5) g/kg, and 42 and 25 (s.e. 2.5) g/kg, respectively. Mean daily live weight gains for the finishing treatments as listed were 714, 1539, 999 and 1186 (s.e. 32.0) g, respectively. Corresponding mean daily carcass gains, carcass weights, ribs joint fat proportions and m. longissimus lipid concentrations were 416, 901, 645 and 774 (s.e. 24.6) g, 252, 296, 336 and 359 (s.e. 5.5) kg, 76, 165, 154 and 210 (s.e. 5.9) g/kg, and 13, 34, 32 and 55 (s.e. 3.5) g/kg. It is concluded that BB had heavier carcasses of better conformation with less ribs joint fat and less intramuscular lipid than AA. Neither breed type had acceptably finished carcasses after 94 days on pasture, but both breed types had acceptably finished carcasses following concentrate feeding for 94 days. The carcasses of the BB animals on pasture for 94 days and then finished on concentrates were not acceptably finished and m. longissimus lipid concentration was < 25 g/kg. In contrast, the carcasses of the AA animals finished on concentrates for 189 days were over fat and m. longissimus lipid concentration was > 65 g/kg.     

The pharmacokinetics of maropitant citrate dosed orally to dogs at 2 mg/kg and 8 mg/kg once daily for 14 days consecutive days

The pharmacokinetics of maropitant were evaluated in beagle dogs dosed orally with Cerenia^® tablets (Pfizer Animal Health) once daily for 14 consecutive days at either 2 mg/kg or 8 mg/kg bodyweight. Noncompartmental pharmacokinetic analysis was performed on the plasma concentration data to measure the AUC_0–24 (after first and last doses), C_t (trough concentration—measured 24 h after each dose), C_max (after first and last doses), t_max (after first and last doses), λ_z (terminal disposition rate constant; after last dose), t_1/2 (after last dose), and CL/F (oral clearance; after last dose). Maropitant accumulation in plasma was substantially greater after fourteen daily 8 mg/kg doses than after fourteen daily 2 mg/kg doses as reflected in the AUC_0–24 accumulation ratio of 4.81 at 8 mg/kg and 2.46 at 2 mg/kg. This is most likely due to previously identified nonlinear pharmacokinetics of maropitant in which high doses (8 mg/kg) saturate the metabolic clearance mechanisms and delay drug elimination. To determine the time to reach steady‐state maropitant plasma levels, a nonlinear model was fit to the least squares (LS) means maropitant C_t values for each treatment group. Based on this model, 90% of steady‐state was determined to occur at approximately four doses for daily 2 mg/kg oral dosing and eight doses for daily 8 mg/kg oral dosing.     

A comparison of Friesian, Aberdeen Angus × Friesian and Belgian Blue × Friesian steers finished at pasture or indoors

Cross-breeding of dairy cows with beef bulls is common in Ireland with the Aberdeen Angus and Belgian Blue beef breeds both widely used. These breeds differ in maturity and consequently in their suitability for production systems differing in intensity and slaughter age. The objective of this study was to compare spring-born Holstein–Friesian (FR), Aberdeen Angus × Holstein–Friesian (AA) and Belgian Blue  × Holstein–Friesian (BB) steers slaughtered off pasture at the end of their second grazing season or slaughtered at the end of the second winter following indoor finishing. Fifty-four (18 per breed type) steers were managed together to 16 months of age. They were then blocked on weight within breed type and assigned to a 3 (breed types) × 2 (finishing strategies) factorial experiment. The two finishing strategies were (i) concentrate supplementation (mean 3.65 kg/day) at pasture for 105 days to slaughter, and (ii) pasture only for 105 days followed by indoor finishing on grass silage plus concentrates for 141 days to slaughter. Mean slaughter and carcass weights per day of age for FR, AA and BB were 852, 802 and 834 (S.E. 13.1) g, and 427, 412 and 452 (S.E. 7.3) g, respectively. Corresponding kill-out proportions, carcass conformation and carcass fat classes were 501, 514 and 542 (S.E. 2.4) g/kg, 1.90, 2.15 and 2.89 (S.E. 0.073), and 3.09, 3.27 and 2.59 (S.E. 0.122), respectively. The response to concentrates at pasture was 101 g live weight and 83 g carcass weight per kg dry matter. It is concluded that there were few differences between FR and AA in carcass growth and composition but BB had heavier carcasses of better conformation with higher proportions of lean meat and high-value lean joints than both FR and AA. Acceptable live weight and carcass weight gains were obtained on pasture plus concentrates but BB and FR carcasses were not acceptably finished off pasture. Both FR and AA produced acceptable carcasses following indoor finishing and BB carcasses, while below the target fat class, were acceptably finished based on internal fat and dissected carcass fat proportions.     

Apheresis in three dogs weighing <14 kg

HistoryCaridianBCT apheresis machines require a ~285 mL priming volume (extracorporeal blood) that is withdrawn from the patient in ~10 minutes. Therefore, apheresis in dogs has generally been limited to dogs > ~20 kg to assure <20% of the blood volume is removed in the priming phase.Animals/physical examinationThree dogs weighing <14 kg (13.6, 10.5, and 9.9 kg) with lymphoma that underwent apheresis.ManagementThe dogs were premedicated for placement of apheresis catheters with hydromorphone (0.1 mg kg^?1) IM. Anesthesia was induced with propofol, to effect, intravenously and general anesthesia was maintained with isoflurane in oxygen. Following catheter placement, dogs were allowed to recover from isoflurane but were kept sedated with either a dexmedetomidine constant rate infusion (CRI) or a propofol CRI. Real time autologous blood priming was not performed in any of the dogs. Instead, priming solutions were composed of a combination of hetastarch, lactated Ringer's solution, and/or autologous blood that was harvested 4 days before the procedure. During apheresis, dogs received anticoagulant citrate‐dextrose, solution‐A (ACD‐A) to prevent clotting and 10% calcium gluconate as needed to maintain normal ionized calcium concentrations. Dogs were monitored for cardiovascular and cardiopulmonary stability, anemia and lactic acidosis.Follow‐upAll of the dogs had cardiovascular and cardiopulmonary values within clinically acceptable ranges. Immediately following apheresis all of the dogs were mildly to moderately anemic (PCV; 17–35%) although none of the dogs required a transfusion or had an increased lactate concentration.ConclusionsDogs as small as 9.9 kg can successfully undergo apheresis with a variety of priming solutions. Dexmedetomidine or propofol given as a CRI provides sufficient sedation for this procedure.     

Cyclic AMP Signalling During Mammalian Sperm Capacitation – Still Largely Terra Incognita

Cyclic AMP is known to play a major role in intracellular signalling during mammalian sperm capacitation. However, despite much research, many of the molecular details of cyclic AMP's involvement remain obscure. In this review, I discuss the following aspects, presenting some original data as illustration where relevant. With respect to cyclic AMP synthesis, uncertainties exist as to the number of forms of adenylyl cyclase that are present in the spermatozoon, whether they are cytosolic or bound to subcellular structures, and which physiological effectors they respond to (e.g. bicarbonate, Ca²⁺, or receptor‐coupled G‐proteins). While net intracellular levels of cyclic AMP in spermatozoa depend upon the relative activities of adenylyl cyclase and phosphodiesterase, there are wide between‐sample variations within species, both in basal levels and in levels attained after activation of the cyclase (e.g. after sperm treatment with bicarbonate). Moreover, minor changes in bulk cyclic AMP levels can result in large changes in cyclic AMP‐dependent functions. Finally, while cyclic AMP levels respond very rapidly to sperm treatment by effectors such as bicarbonate and Ca²⁺ (key components of capacitating media), there are big discrepancies between the rates of functional response. For example, enhancement of motility and collapse of phospholipid asymmetry take place within a few minutes, whereas more than 1 h of exposure to capacitating conditions is needed for cyclic AMP‐dependent protein tyrosine phosphorylation to become detectable or for the sperm population to attain a capacitated state.     

Energy and protein requirements for growth of Holstein × Gyr heifers

There is little information regarding the nutritional requirements for dairy heifers, leading the majority of nutrient requirement systems to consider dairy heifers to be similar to beef heifers. Therefore, we evaluated the muscle protein metabolism and physical and chemical body composition of growing Holstein × Gyr heifers and estimated the energy and protein requirements. We performed a comparative slaughter experiment with 20 Holstein × Gyr heifers at an initial body weight of 218 ± 36.5 kg and an average age of 12 ± 1.0 months. Four heifers were designated as the reference group, and the 16 remaining heifers were fed ad libitum . The 16 heifers were distributed using a completely randomized design in a 2 × 2 factorial arrangement with two roughages (corn silage or sugarcane) and two concentrate levels (30 or 50%) for 112 days. Greater (p  <  0.05) values for fractional rates of muscle protein synthesis, degradation and accretion were observed for heifers that were fed 50% concentrate. The following equations were obtained to estimate the net energy for gain (NE _g) and net protein for gain (NP _g): NE _g (Mcal/day) = 0.0685 × EBW ^0.75 × EBWG ^1.095 and NP _g (g/day) = 203.8 × EBWG  ? 14.80 × RE , respectively, in which EBW is the empty body weight, EBWG is the empty body weight gain and RE is the retained energy. We concluded that increased rates of protein turnover are achieved when a greater quality diet is provided. In the future, these results can be used to calculate the nutritional requirements for growth of Holstein × Gyr heifers after equation validation rather than using the recommendations provided by other systems, which use values developed from beef heifers, to determine the nutritional requirements of dairy cattle.